The overall objective concerns behavioral and biochemical genetic mechanisms involved in maintenance of melanistic polymorphisms. Behavioral emphasis is on mating systems and territorial aggression relative to microhabitat selection in Drosophila melanogaster. Theories of the significance of territorial behavior relative to sexual selection are explored. Biochemical emphasis is upon the role of beta-alanine in stiffening, tanning, and melanization of the cuticular exoskeleton. Attention is given to behavioral modification relative to such exoskeletal characteristics. Attention is also given to the role of omega amino acids, such as beta-alanine, in the formation of radiation screening pigments in animals and plants. The fungus, Morchella esculenta is used for this part of the study. Electron microscopic autoradiography is used extensively.